Calculation Of Radius Research Articles

Methodical evaluation of Boyle temperatures using Mayer sampling Monte Carlo with application to polymers in implicit solvent.

The Boyle temperature, TB, for an n-segment polymer in solution is the temperature where the second osmotic virial coefficient, A2, is zero. This characteristic is of interest for its connection to the polymer condensation critical temperature, particularly for n → ∞. TB can be measured experimentally or computed for a given model macromolecule. For the latter, we present and examine two approaches, both based on the Mayer-sampling Monte Carlo (MSMC) method, to calculate Boyle temperatures as a function of model parameters. In one approach, we use MSMC calculations to search for TB, as guided by the evaluation of temperature derivatives of A2. The second approach involves numerical integration of an ordinary differential equation describing how TB varies with a model parameter, starting from a known TB. Unlike general MSMC calculations, these adaptations are appealing because they neither invoke a reference for the calculation nor use special averages needed to avoid bias when computing A2 directly. We demonstrate these methods by computing TB lines for off-lattice linear Lennard-Jones polymers as a function of chain stiffness, considering chains of length n ranging from 2 to 512 monomers. We additionally perform calculations of single-molecule radius of gyration Rg and determine the temperatures Tθ, where linear scaling of Rg2 with n is observed, as if the polymers were long random-walk chains. We find that Tθ and TB seem to differ by 6% in the n → ∞ limit, which is beyond the statistical uncertainties of our computational methodology. However, we cannot rule out systematic error relating to our extrapolation procedure as being the source of this discrepancy.

Analysis of health resorts in Bulgaria and calculation of the adaptation radius for outgoing tourism in the country

The article examines the types of health resorts, the resources used for treatment and the distribution of resorts across the country. There is also a calculation of the adaptation radius for outbound tourism from Bulgaria.

Research on the performance optimization of the cam linkage mechanism for marine diesel engines

Abstract In this paper, the impact of friction and wear in the flat bottom mechanism of a diesel engine on the reliability and durability of the valve train is investigated. A method for establishing a dynamic contact model is proposed, including the establishment of the cam profile equation, force analysis at the contact point, calculation of the curvature radius, and derivation of contact stress. Through the derivation of wear depth and structural optimization analysis, the proposed method can be used to optimize the cam profile and improve the service life and work efficiency of the valve train. The results show that the optimized cam follower’s life is increased by 31.8%, and the contact stress is decreased by 16.5%. This study is of great significance for improving the power and efficiency of diesel engines.

Investigating the properties of ortho-positronium in liquid scintillators under oxygen quenching

Investigating the mechanism of positron annihilation in liquid-scintillator based neutrino experiments could be helpful for positron reconstruction algorithms and positron-electron discrimination analysis. Based on this, we utilize a novel positron annihilation lifetime spectrometer to characterize a series of liquid scintillator samples without direct contact with the positron source by applying the anti-coincidence method, which facilitates the measurement of liquids with high accuracy and low background. We obtain an ortho-positronium (o-Ps) lifetime value of 3.02 ns for liquid scintillators composed of linear alkylbenzene and two solutes, and we also measure liquid scintillator samples by bubbling different gases to study the interaction of oxygen dissolved with positronium. The discussion of the annihilation behavior of o-Ps in liquid scintillators further clarify the factors affecting the lifetime and intensity of o-Ps, and the calculation of annihilation rate and free volume radius within the samples has potential applications in characterizing gas solubility and free volume in liquids with o-Ps as probe.

Generalized geometric pore size distribution code GPSD-3D for periodic systems composed of monodisperse spheres

The generalized geometric pore size distribution P(r;rp|rc) as function of pore radius r, probe sphere radius rp, and coating thickness rc for a periodic two-dimensional system composed of circles (GPSD-2D) had been defined recently. For rp=rc=0 it reduces to the widely accepted pore radius distribution P(r) introduced by Gelb and Gubbins. The three-dimensional counterpart GPSD-3D for periodic systems composed of spheres is implemented here using an efficient Voronoi-based semi-analytic strategy that offers significant advantages compared with both a grid-based implementation and constrained nonlinear optimization with respect to speed, precision and memory requirements. Moreover, GPSD-3D is fully parallelized using OpenMP. Program summaryProgram title:GPSD-3DCPC library link to program files:https://doi.org/10.17632/ntcr87fgr5.1Developers repository link:https://github.com/mkmat/CODE-GPSD-3DLicensing provisions: MITProgramming languages:fortran, c++, perlNature of problem: Calculation of a set of pore radii for a user-provided configuration of (material) spheres contained in a periodic three-dimensional, rectangular box. This set depends on the user-specified radius rp of a probe sphere, and a user-specified hypothetical coating thickness rc of the material spheres. The variable size of the set, and thus the resolution of the resulting generalized geometric pore size distribution increases linearly with computing time.Solution method: Analytic calculation of pore radii from the Voronoi faces for the case of monodisperse systems, constrained nonlinear optimization or grid-based approach for polydisperse systems.Additional comments: This code requires a c++ compiler such as g++, a OpenMP-supporting fortran compiler such as gfortran, perl, and the voro++ library. Download links will be automatically provided during installation of GPSD-3D.

Табиғи және техногендік сипаттағы өрттердің зиянды шығарындыларын талдау

Over the past decade, the number of natural and man-made fires has increased, which lead to great casualties, serious environmental pollution and large economic losses. The paper presents the statistics of forest and steppe fires for 2022 in the Republic Kazakhstan, and the statistics of deaths in emergencies associated with a fire. During forest fires, the composition of combustion products depends on the composition of wood and the conditions of its combustion. Accordingly, the emissions are carbon dioxide, nitrogen, carbon monoxide and sulfur dioxide. Also, the calculation of the explosion radius in the diesel fuel warehouse was made. It has been established that the maximum explosion pressure and flame temperature for mixtures of limiting composition are practically constant at different initial pressures. For a mixture of constant composition, these characteristics change significantly with an increase in the initial pressure. The composition of combustion products is analyzed at various initial pressures. From the analysis of time scales, area, facilities and equipment, ignition sources, types of emergency substances and liability, statistical results show that the most dangerous area is the loading and unloading area and the most vulnerable facility and equipment are storage tanks. Meanwhile, the proportions of ignition sources are distributed so evenly that the prevention of fire and explosion must be equally focused on several factors of influence. A vapor cloud explosion may be the most common type of accident at oil depots, and management responsibility dominates all accident causes. A visual interpretation of the obtained results is presented.

Incident during construction of an underwater passage by directional drilling

Relevance. This paper considers the issue of construction of underwater passages of trunk pipelines by the directional drilling method using concrete weight coated pipes. This issue is relevant, since at the present moment there is no standards and technical documentation regulating the calculation procedure of the minimum allowable elastic bend radius of a pipeline with concrete coating in a well. There are situations when design institutes made incorrect design decisions as a result, the pipe string got stuck during works. Those incidents led to unnecessary economic expenditures and a delay in the work implementation plan. Aim. To study the issues which related with the sticking of the pipe string during the construction of the underwater passage of the main pipeline by the method of directional drilling; calculate the minimum allowable elastic bend radius of a pipeline with concrete coating and the actual parameters of the pilot drillhole. Objects. An underwater passage of a trunk pipeline constructed by the method of directional drilling. Methods. Study of standards and technical documents on the construction of underwater crossings of main pipelines and an analysis of the incident in which a pipeline with concrete weight coating got stuck. Results. The authors substantiate the calculation of the minimum allowable elastic bend radius of a pipeline with a concrete coating based on the requirements of domestic standards and technical documentation. The authors have calculated this value by an analytical method, based on studies of the bending stiffness of concrete structures by foreign scientists, as well as actual parameters of the pilot drillhole. The obtained results of the studied values were analyzed and a conclusion was given about the causes of the incident associated with the sticking of the pipe string.

Improved hourly estimate of aerosol optical thickness over Asian land by fusing geostationary satellites Fengyun-4B and Himawari-9

Asian over-land aerosols are complexities due to a mixture of anthropogenic air pollutants and natural dust. The accuracy of the aerosol optical thickness (AOT) retrieved from the satellite is crucial to their application in the aerosol data assimilation system. Fusion of AOTs with high spatiotemporal resolution from next-generation geostationary satellites such as Fengyun-4B (FY-4B) and Himawari-9, provides a new high-quality dataset capturing the aerosol spatiotemporal variability for data assimilation. This study develops a complete fusion algorithm to estimate the optimal AOT over-land in Asia from September 2022 to August 2023 at 10 km × 10 km resolution with high efficiency. The data fusion involves four steps: (1) investigating the spatiotemporal variability of FY-4B AOT within the past 1 h and 12 km radius calculation domain; (2) utilizing the aerosol spatiotemporal variability characteristics to estimate FY-4B pure and hourly merged AOTs; (3) performing bias corrections for FY-4B and Himwari-9 hourly merged AOT for different observation times and seasons considering pixel-level errors for each satellite; (4) fusing the bias-corrected FY-4B and Himawari-9 hourly merged AOT based on maximum-likelihood estimation (MLE) method. Compared to the original FY-4B AOT, validation with AERONET observation confirms that the root mean square error (RMSE) of hourly merged FY-4B AOT decreases by around 40.6 % and the correlation coefficient (CORR) increases by about 27.8 %. Compared to FY-4B and Himawari-9 merged AOT, the fused AOT significantly decreases (increases) RMSE (CORR) by around 24.7 % (7.3 %) and 20.2 % (5.6 %). In addition, fused AOT is double the number of single-sensor merged AOT. Fusion aerosol map accurately describes the spatial and temporal variations in Asian regions controlled by air pollution and dust storms. Further studies are required for other landscapes with different satellite combinations to promote the application in the data assimilation system.

Calculation Model of Drainage Radius of Single-Layer/Multi-Layer Commingled Gas Production Wells in a Closed Constant-Volume Gas Reservoir and Its Application

Gas drainage radius is the most important parameter for determining reasonable well spacing. However, the drainage radius of both single-layer and multi-layer commingled gas production wells cannot be directly obtained through reservoir well tests. In order to address the above challenge, for single-layer gas production wells in a closed constant-volume gas reservoir, a calculation model for drainage radius is derived using the modified flowing material balance method. The results indicate that the calculated error of this model is only 0.73% and much smaller than that of the flowing material balance method (5.78%), implying its high accuracy. For multi-layer commingled gas production wells, another calculation model of drainage radius is established by coupling the pseudo-steady-state production capacity equation with the material balance principle. The research results demonstrate that the novel calculation model has a maximum relative error of only 2.33% and requires only two production profile tests to rapidly calculate the drainage radius of each layer within the gas reservoir, suggesting its satisfactory simplicity, significant efficiency and high precision. The proposed calculation models of drainage radius achieve a convenient and rapid calculation for both single-layer and multi-layer commingled gas production wells, and fill the theoretical gap in efficient calculation of drainage radius for a closed constant-volume gas reservoir.

Piecewise circular interface construction using height functions

AbstractA piecewise circular interface construction (PCIC) method is described, where height functions based curvature estimates are directly utilised for accurate interface reconstruction under the framework of volume of fluid method. The present work is an attempt to develop a robust and accurate higher order interface reconstruction algorithm that is capable of accurate simulation of surface tension dominated flows. The proposed hybrid method (H‐PCIC) is thus able to take advantage of merits of both PCIC and HF methods, achieving at least second order convergence with respect to both interface reconstruction and curvature computation. This is in addition to the significantly superior quality of the reconstructed interface with respect to PLIC methods. This seamless blending of the HF and PCIC quantities is enabled by c0‐correction procedures applied to base PLIC and initial PCIC steps. More recent variants of the height function method with variable stencil size are used for calculation of radius of curvature. The capability of this proposed method towards simulation of flow problems within a well‐balanced two‐phase solver is established with help of multiple complex two‐phase flow problems. This validation exercise also demonstrates the capability of PCIC class of methods towards solutions of two‐phase flows with intricate physics.

An algorithm for calculating spectral radius of $ s $-index weakly positive tensors

<abstract><p>In this paper, we introduced $ s $-index weakly positive tensors and discussed the calculation of the spectral radius of this kind of nonnegative tensors. Using the diagonal similarity transformation of tensor and Perron-Frobenius theory of nonnegative tensor, the calculation method of the maximum $ H $-eigenvalue of $ s $-index weakly positive tensors was given. A variable parameter was introduced in each iteration of the algorithm, which is equivalent to a translation transformation of the tensor in each iteration to improve the calculation speed. At the same time, it was proved that the algorithm is linearly convergent for the calculation of the spectral radius of $ s $-index weakly positive tensors. The final numerical example shows the effectiveness of the algorithm.</p></abstract>

Calculation of the input laser pulse radius's impact on stimulated Raman scattering under self-focusing conditions

Calculation of the input laser pulse radius's impact on stimulated Raman scattering under self-focusing conditions

A New Elementary Method for Determining the Tip Radius and Young's Modulus in AFM Spherical Indentations.

Atomic force microscopy (AFM) is a powerful tool for characterizing biological materials at the nanoscale utilizing the AFM nanoindentation method. When testing biological materials, spherical indenters are typically employed to reduce the possibility of damaging the sample. The accuracy of determining Young's modulus depends, among other factors, on the calibration of the indenter, i.e., the determination of the tip radius. This paper demonstrates that the tip radius can be approximately calculated using a single force-indentation curve on an unknown, soft sample without performing any additional experimental calibration process. The proposed method is based on plotting a tangent line on the force indentation curve at the maximum indentation depth. Subsequently, using equations that relate the applied force, maximum indentation depth, and the tip radius, the calculation of the tip radius becomes trivial. It is significant to note that the method requires only a single force-indentation curve and does not necessitate knowledge of the sample's Young's modulus. Consequently, the determination of both the sample's Young's modulus and the tip radius can be performed simultaneously. Thus, the experimental effort is significantly reduced. The method was tested on 80 force-indentation curves obtained on an agarose gel, and the results were accurate.

A generalized Kirkwood implicit solvent for the polarizable AMOEBA protein model.

Computational simulation of biomolecules can provide important insights into protein design, protein-ligand binding interactions, and abinitio biomolecular folding, among other applications. Accurate treatment of the solvent environment is essential in such applications, but the use of explicit solvents can add considerable cost. Implicit treatment of solvent effects using a dielectric continuum model is an attractive alternative to explicit solvation since it is able to describe solvation effects without the inclusion of solvent degrees of freedom. Previously, we described the development and parameterization of implicit solvent models for small molecules. Here, we extend the parameterization of the generalized Kirkwood (GK) implicit solvent model for use with biomolecules described by the AMOEBA force field via the addition of corrections to the calculation of effective radii that account for interstitial spaces that arise within biomolecules. These include element-specific pairwise descreening scale factors, a short-range neck contribution to describe the solvent-excluded space between pairs of nearby atoms, and finally tanh-based rescaling of the overall descreening integral. We then apply the AMOEBA/GK implicit solvent to a set of ten proteins and achieve an average coordinate root mean square deviation for the experimental structures of 2.0 Å across 500ns simulations. Overall, the continued development of implicit solvent models will help facilitate the simulation of biomolecules on mechanistically relevant timescales.

Study of the structure and intensity of density currents in the shelf-slope region in the Antarctic

The research involves the examination of modeling outcomes regarding the density structure and baroclinic dynamics of Antarctic shelf waters (ASW) within the shelf-slope area, encompassing a wide range of extreme weather conditions. We used a small-scale non-hydrostatic Fluidity-ICOM model to understand the formation and persistence of quasi-stationary polynyas in the Antarctic, which play a role in enhancing the formation of ASW. The salt fluxes, or buoyancy, are calculated for different forms of ice formation, namely static ice formation in young ice-covered polynyas and dynamic intra-water ice formation, which is considered the most effective and occurs in open water polynyas. Based on the intensification of ASW formation and its spread, three distinct modes of propagation along the continental slope have been identified: non-wave or subcritical mode, vortex mode, and wave or supercritical mode, which is characterized by rapid flow. The classification into different modes is determined by the internal Froude number (Fr) estimates. At the moment when the most developed stage of near-bottom density currents are transformed on a slope, the spatial dimensions of meanders, eddies, or frontal waves were found to be similar in magnitude, as well as their thickness. This observation aligns with model calculations of the local baroclinic Rossby deformation radius (RdL) for these currents. These findings agree with comparable assessments of the baroclinic Rossby deformation radius (RdL) for the Antarctic Slope Front (ASF) in the Commonwealth Sea, which were based on field observations. Additionally, the calculated propagation velocities of density currents and the density gradients at their boundaries coincide with the data obtained from field measurements. By estimating the volumetric fluxes (qv) and specific fluxes (ql) of ASW along the continental slope near the Cape Darnley coastal polynya area in the Commonwealth Sea, we can determine the contribution of ASW cascading to the formation of bottom waters under different flux regimes. The precision and accuracy of the qv and ql estimates are ensured through small-scale calculations using the non-hydrostatic Fluidity-ICOM model. These calculations consider the occurrences of intensified ASW formation in open water polynyas. Numerical experiments have revealed that a four-fold increase in a spatial step X results in an underestimation of qv by approximately 30%. As a consequence, in large-scale and even mesoscale hydrostatic models, such underestimation of qv and ql may be unsatisfactory (several times lower).

Combining Experiments and Simulations to Examine the Temperature-Dependent Behavior of a Disordered Protein.

Intrinsically disordered proteins are a class of proteins that lack stable folded conformations and instead adopt a range of conformations that determine their biochemical functions. The temperature-dependent behavior of such disordered proteins is complex and can vary depending on the specific protein and environment. Here, we have used molecular dynamics simulations and previously published experimental data to investigate the temperature-dependent behavior of histatin 5, a 24-residue-long polypeptide. We examined the hypothesis that histatin 5 undergoes a loss of polyproline II (PPII) structure with increasing temperature, leading to more compact conformations. We found that the conformational ensembles generated by the simulations generally agree with small-angle X-ray scattering data for histatin 5, but show some discrepancies with the hydrodynamic radius as probed by pulsed-field gradient NMR spectroscopy, and with the secondary structure information derived from circular dichroism. We attempted to reconcile these differences by reweighting the conformational ensembles against the scattering and NMR data. By doing so, we were in part able to capture the temperature-dependent behavior of histatin 5 and to link the observed decrease in hydrodynamic radius with increasing temperature to a loss of PPII structure. We were, however, unable to achieve agreement with both the scattering and NMR data within experimental errors. We discuss different possible reasons for this including inaccuracies in the force field, differences in conditions of the NMR and scattering experiments, and issues related to the calculation of the hydrodynamic radius from conformational ensembles. Our study highlights the importance of integrating multiple types of experimental data when modeling conformational ensembles of disordered proteins and how environmental factors such as the temperature influence them.

THE INFLUENCE OF INHOMOGENEOUS RADIAL PROFILE OF WAXY CRUDE OIL TEMPERATURE AND SHEAR STRESS IN A STOPPED PIPELINE ON THE RESTART PUMPING PRESSURE FOR «USA — UKHTA» MAIN PIPELINE

The purpose of this work is to calculate the shear pressure gradient and shear radius of paraffinic oil in a stopped pipeline as functions of the longitudinal coordinate z along the axis of the stopped section, as well as the minimum shear pressure difference between the ends of the pipeline, taking into account the non-uniform cooling of oil over time in the radial direction, leading to a significant increase in static shear stress with distance from the center to the edge of the pipe. Using a simple mathematical model that describes the non-uniform cooling of oil along the radius r and along the longitudinal coordinate z along the pipe axis due to heat conduction, it is shown that with a smooth increase in start-up pressure at the beginning of a stopped pipeline section, the cooling oil can shift not along the pipe wall, but along its central part, the radius of which depends both on the oil cooling time and on the z coordinate along the pipeline axis. Calculations show that the process of cooling of the stopped oil can be conditionally divided into three stages. At the first time stage of cooling, the oil near the pipeline axis does not cool down to the temperature of the appearance of static shear stress, that is, it is actually Newtonian and there is no problem with starting this oil layer. At the third time stage of cooling, when the oil cools below the temperature of the onset of paraffin mass crystallization, that is, it turns into a viscous-plastic one in the entire volume of the oil pipeline, the calculation of the minimum pressure difference between the ends of the pipe required to start the oil pipeline can be carried out using a method that qualitatively coincides with the method described in [27]. Finally, in the second cooling time step, which occupies an intermediate position between the first and third steps, the pipeline can be divided into two sections in the longitudinal direction. The behavior of oil in the first section, adjacent to the beginning of the pipeline, resembles the behavior of oil in the entire pipeline at the end of the first stage of cooling, and
 in the second section, extending from the end of the first section to the end of the pipe, the oil behaves similarly to the oil in the entire pipeline in the third temporary stage of cooling. In this case, the boundary between the first and second sections of the pipe during the second temporary stage of cooling is displaced from the end of the pipeline to its beginning.
 It is shown that calculations of the shear pressure required to resume the pumping of cooled oil, which do not take into account the inhomogeneous cooling of oil in the pipe cross section, can overestimate the desired pressure value. This fact should be taken into account in practice when assessing the restart pressure and the safe shutdown time of a pipeline transporting highly pourable oils using the “hot” pumping method. All laboratory measurements of the thermal parameters of oil, as well as calculations of pressure and shear radius, were carried out on the example of the Usa-Ukhta main oil pipeline of JSC Transneft-North.

Importance of the average radius of coal particles on determining the methane diffusion coefficient.

The average radius of coal particles is an estimate of the diffusion path in the particle method for determining the diffusion coefficient. It is currently calculated using the arithmetic mean of coal particle sieved intervals. This calculation, however, ignores the coal particle size distribution, resulting in significant deviations when calculating the gas diffusion coefficient. An appropriate average radius calculation method should consider the particle size distribution and the physical essence of diffusion. To accomplish this, a series of methods for calculating the mean particle diameters and their physical significance were reviewed. Next, coal samples were sieved into three intervals, and gas diffusion tests and laser particle size distribution were conducted. Results show that coal particles are within the sieving interval, ranging from 42.01 to 76.18%. By solving the diffusion coefficients using four mean particle diameters based on particle size distribution and diffusive mass transfer, the difference between the arithmetic mean value and these diameters is up to 89.06%. [Formula: see text] and [Formula: see text] are preferred for the calculation of the average radius since they are compatible with coal particle shape and the physical meaning of diffusive mass transfer.

An optical-input Maximum Likelihood Estimation feedback system demonstrated on tokamak horizontal equilibrium control

A readily parallelized Maximum Likelihood Estimation (MLE) algorithm with linear computational complexity is demonstrated in real time using only measurements from an extreme ultraviolet (EUV) diagnostic to control the horizontal position of a tokamak plasma. A set of trial emissivity profiles are parameterized by the control quantity of interest (Rm), and the MLE is identified from the profile which minimizes the signal reconstruction residual. The algorithm depends on an empirically determined likelihood function with exponential form. EUV emission (λ≈ 15 eV-1 keV) is captured in a poloidal plane by four 16-channel AXUV diodes mounted at different poloidal angles with radial and angular resolution sufficient to discern plasma equilibrium evolution in HBT-EP. Calculations of the plasma major radius by the system are consistent within diagnostic uncertainty for the majority of the discharge with those of: a weighted average of vertical soft X-ray or EUV chords, magnetic sensors, and an equilibrium reconstruction. The feedback system corrects for a horizontal displacement of the major radius equal to 20% of the plasma minor radius by adjusting the vertical field produced from 40 in-vessel control coils in real time. The MLE calculation is performed on a GPU in a 15μs cycle, with similar performance in this application to a simple weighted average of vertical chords. Results demonstrate horizontal position control using magnetic actuators and an optical observer.

Bayes goes fast: Uncertainty quantification for a covariant energy density functional emulated by the reduced basis method

A covariant energy density functional is calibrated using a principled Bayesian statistical framework informed by experimental binding energies and charge radii of several magic and semi-magic nuclei. The Bayesian sampling required for the calibration is enabled by the emulation of the high-fidelity model through the implementation of a reduced basis method (RBM)—a set of dimensionality reduction techniques that can speed up demanding calculations involving partial differential equations by several orders of magnitude. The RBM emulator we build—using only 100 evaluations of the high-fidelity model—is able to accurately reproduce the model calculations in tens of milliseconds on a personal computer, an increase in speed of nearly a factor of 3,300 when compared to the original solver. Besides the analysis of the posterior distribution of parameters, we present model calculations for masses and radii with properly estimated uncertainties. We also analyze the model correlation between the slope of the symmetry energy L and the neutron skin of 48Ca and 208Pb. The straightforward implementation and outstanding performance of the RBM makes it an ideal tool for assisting the nuclear theory community in providing reliable estimates with properly quantified uncertainties of physical observables. Such uncertainty quantification tools will become essential given the expected abundance of data from the recently inaugurated and future experimental and observational facilities.